IDispatch::GetIDsOfNames

Article
11/18/2015

A version of this page is also available for

4/8/2010

This method maps a single member name and an optional set of parameter names to a corresponding set of integer dispatch identifiers (DISPIDs), which can then be used on subsequent calls to Invoke.

Syntax

HRESULT GetIDsOfNames( 
  REFIID riid, 
  OLECHAR FAR* FAR* rgszNames, 
  unsigned int cNames, 
  LCID lcid, 
  DISPID FAR* rgDispId 
);

Parameters

riid
[in] Reserved for future use; set to IID_NULL.

rgszNames
[in] Passed-in array of names to be mapped.

cNames
[in] Count of the names to be mapped.

lcid
[in] Locale context in which to interpret the names.

rgDispId
[out] Caller-allocated array, each element of which contains an identifier that corresponds to one of the names passed in the rgszNames array. The first element represents the member name. The subsequent elements represent each of the member's parameters.

Return Value

The following table shows the return values for this function.

Value	Description
S_OK	Success.
E_OUTOFMEMORY	Out of memory.
DISP_E_UNKNOWNNAME	One or more of the names were not known. The returned array of DISPIDs contains DISPID_UNKNOWN for each entry that corresponds to an unknown name.
DISP_E_UNKNOWNLCID	The locale identifier (LCID) was not recognized.

Remarks

An IDispatch implementation can associate any positive integer identifier value with a given name. Zero is reserved for the default, or Value property; –1 is reserved to indicate an unknown name; and other negative values are defined for other purposes.

For example, if GetIDsOfNames is called, and the implementation does not recognize one or more of the names, it returns DISP_E_UNKNOWNNAME, and the rgDispId array contains DISPID_UNKNOWN for the entries that correspond to the unknown names.

The member and parameter DISPIDs must remain constant for the lifetime of the object. This allows a client to obtain the DISPIDs once, and cache them for later use.

When GetIDsOfNames is called with more than one name, the first name (rgszNames[0]) corresponds to the member name, and subsequent names correspond to the names of the member's parameters.

The same name may map to different DISPIDs, depending on context. For example, a name may have a DISPID when it is used as a member name with a particular interface, a different identifier as a member of a different interface, and different mapping for each time it appears as a parameter.

The IDispatch interface binds to names at run time. To bind at compile time instead, an IDispatch client can map names to DISPIDs by using the ITypeLib, ITypeLib2, ITypeInfo, ITypeInfo2, and ITypeComp interfaces. This allows a client to bind to members at compile time and avoid calling GetIDsOfNames at run time.

The implementation of GetIDsOfNames is case insensitive. Users that need case-sensitive name mapping should use type information interfaces to map names to DISPIDs, rather than call GetIDsOfNames.

Example

The following code from the Lines sample file Lines.cpp implements the GetIDsOfNames member function for the CLine class. The ActiveX or OLE object uses the standard implementation, DispGetIDsOfNames.

STDMETHODIMP 
CLine::GetIDsOfNames(
REFIID riid,
OLECHAR FAR* FAR* rgszNames,
UINT cNames,
LCID lcid,
DISPID FAR* rgDispId)
{
return DispGetIDsOfNames(m_ptinfo, rgszNames, cNames, rgDispId);
}

The following code might appear in an ActiveX client that calls GetIDsOfNames to get the DISPID of the CLine Color property.

HRESULT hresult;
IDispatch FAR* pdisp = (IDispatch FAR*)NULL;
DISPID dispid;
OLECHAR FAR* szMember = "color";
// Code that sets a pointer to the dispatch (pdisp) is omitted.
hresult = pdisp->GetIDsOfNames(
IID_NULL,
&szMember,
1, LOCALE_SYSTEM_DEFAULT,
&dispid);

Requirements

Header	oaidl.h, oaidl.idl
Library	oleaut32.lib, uuid.lib
Windows Embedded CE	Windows CE 2.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later

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